8 BULLETIN 1064, U. S. DEPARTMENT OF AGRICULTURE. 



SECTIONING AND MOUNTING. 



Kelatively thin sections (10 to 48 microns) were made from the 

 greater number of the specimens studied. For this purpose a sliding 

 microtome of the Jung type with the Thomson modification was 

 used. Some observations were made with a hand lens on smoothly 

 cut surfaces. The sections to be preserved or photographed were 

 stained with safranin (water-alcohol mixture), dehydrated with 

 alcohol, cleared with xylol, and mounted in Canada balsam. Micro- 

 scopic examinations were also made of microtome or hand sections 

 temporarily mounted in glycerine alcohol (50-50 mixture). 



AMOUNT OF MATERIAL. 



Samples were obtained each month during the 1916 and 1917 

 seasons, from 15 trees, 5 from each of the three experimental plots. 13 

 Specimens were also examined at the end of each season from 50 

 trees on each plot and from 50 unturpentined trees from the same 

 locality. In addition to this, considerable material was collected 

 from Bogalusa, La. ; Kokomo and Gulfport, Miss. ; Daytona, Boni- 

 fay, and the Forest Service experiments and leases near Camp 

 Pinchot, Fla. More than 4,500 microscopic mounts were prepared 

 and examined. 



PROCESS OF TURPENTINING. 



METHODS OF WOUNDING OR SCARIFYING THE TREES. 



In ordinary methods of turpentining the oleoresin is made to flow 

 from the tree by periodically cutting a wound or streak through the 

 bark and for a variable distance into the sapwood. In the United 

 States the cut or streak is generally made in the form of a some- 

 what flattened V, the point or peak of which is at the center of the 

 face. (PL I, fig. 4.) The wound used by the French is different 

 in shape (PL I, fig. 6), and smaller. The Germans recently have 

 been practicing modifications of the American system. 



Except for the general type of face used, the commercial practice 

 of turpentining is not standardized in the United States. The size 

 of the faces used, the amount of bark bars between faces, and the 

 dimensions of the streak or wound cut each week, show marked 

 differences in different operations. The depth of the weekly chip- 

 ping may vary from one-half inch to 1| inches (bark not included), 

 and the height of the chipping from one-half inch to 1 inch, or 

 enough, as some operators say, to " keep ahead of the lightwood." 14 



13 When more than one face was on a tree each face was indicated by a letter descrip- 

 tive of its general position with reference to points of the compass, as N., S., E., W. 

 (See, for instance, tree 1, fig. 1.) 



J * See p. 31. 



